The cleansing of skin with surface-active cleansing preparations has become a focus of great interest. Many people, particularly, urban Americans, wash and scrub their skin with various surface-active preparations several times a day. Ideal skin cleansers should cleanse the skin gently, causing little or no irritation, without defatting or overdrying the skin or leaving it taut after frequent routine use. Most lathering soaps, liquids and bars included, fail in this respect.
Synthetic detergent bars, frequently referred to as "syndet bars," are well known and are becoming increasingly popular. However, widespread replacement of soap bars by syndet bars has not so far been possible for a variety of reasons, primarily the different physical characteristics of syndet bars as compared to soap bars, e.g., smear or bar messiness, lather and rinse quality.
The soap bar literature is full of references to technology which improved bar soap mildness. However, to improve bar soap mildness without processing and/or lather negatives requires a delicate balancing act.
It will be appreciated that rather stringent requirements for skin cleansers limit the choice of surface-active agents and final formulations represent some degree of compromise. Mildness is often obtained at the expense of effective cleansing and lathering. Conversely, mildness may be sacrificed for either preferred lathering characteristics, bar firmness, product stability, or all of these.